diff --git a/internal/graphicsdriver/opengl/context.go b/internal/graphicsdriver/opengl/context.go
index 7a4d26afd..328e47204 100644
--- a/internal/graphicsdriver/opengl/context.go
+++ b/internal/graphicsdriver/opengl/context.go
@@ -134,7 +134,7 @@ func (c *context) bindTexture(t textureNative) {
 	if c.lastTexture == t {
 		return
 	}
-	c.bindTextureImpl(t)
+	c.ctx.BindTexture(gl.TEXTURE_2D, uint32(t))
 	c.lastTexture = t
 }
 
@@ -142,7 +142,7 @@ func (c *context) bindRenderbuffer(r renderbufferNative) {
 	if c.lastRenderbuffer == r {
 		return
 	}
-	c.bindRenderbufferImpl(r)
+	c.ctx.BindRenderbuffer(gl.RENDERBUFFER, uint32(r))
 	c.lastRenderbuffer = r
 }
 
@@ -150,7 +150,7 @@ func (c *context) bindFramebuffer(f framebufferNative) {
 	if c.lastFramebuffer == f {
 		return
 	}
-	c.bindFramebufferImpl(f)
+	c.ctx.BindFramebuffer(gl.FRAMEBUFFER, uint32(f))
 	c.lastFramebuffer = f
 }
 
@@ -160,7 +160,7 @@ func (c *context) setViewport(f *framebuffer) {
 		// On some environments, viewport size must be within the framebuffer size.
 		// e.g. Edge (#71), Chrome on GPD Pocket (#420), macOS Mojave (#691).
 		// Use the same size of the framebuffer here.
-		c.setViewportImpl(f.width, f.height)
+		c.ctx.Viewport(0, 0, int32(f.width), int32(f.height))
 
 		// glViewport must be called at least at every frame on iOS.
 		// As the screen framebuffer is the last render target, next SetViewport should be
@@ -181,7 +181,7 @@ func (c *context) getScreenFramebuffer() framebufferNative {
 
 func (c *context) getMaxTextureSize() int {
 	c.maxTextureSizeOnce.Do(func() {
-		c.maxTextureSize = c.maxTextureSizeImpl()
+		c.maxTextureSize = c.ctx.GetInteger(gl.MAX_TEXTURE_SIZE)
 	})
 	return c.maxTextureSize
 }
@@ -231,10 +231,6 @@ func (c *context) blend(blend graphicsdriver.Blend) {
 	)
 }
 
-func (c *context) scissor(x, y, width, height int) {
-	c.ctx.Scissor(int32(x), int32(y), int32(width), int32(height))
-}
-
 func (c *context) newTexture(width, height int) (textureNative, error) {
 	t := c.ctx.CreateTexture()
 	if t <= 0 {
@@ -260,10 +256,6 @@ func (c *context) newTexture(width, height int) (textureNative, error) {
 	return textureNative(t), nil
 }
 
-func (c *context) bindFramebufferImpl(f framebufferNative) {
-	c.ctx.BindFramebuffer(gl.FRAMEBUFFER, uint32(f))
-}
-
 func (c *context) framebufferPixels(buf []byte, f *framebuffer, x, y, width, height int) error {
 	if got, want := len(buf), 4*width*height; got != want {
 		return fmt.Errorf("opengl: len(buf) must be %d but was %d at framebufferPixels", got, want)
@@ -285,14 +277,6 @@ func (c *context) framebufferPixelsToBuffer(f *framebuffer, buffer buffer, width
 	c.ctx.BindBuffer(gl.PIXEL_PACK_BUFFER, 0)
 }
 
-func (c *context) activeTexture(idx int) {
-	c.ctx.ActiveTexture(uint32(gl.TEXTURE0 + idx))
-}
-
-func (c *context) bindTextureImpl(t textureNative) {
-	c.ctx.BindTexture(gl.TEXTURE_2D, uint32(t))
-}
-
 func (c *context) deleteTexture(t textureNative) {
 	if !c.ctx.IsTexture(uint32(t)) {
 		return
@@ -303,10 +287,6 @@ func (c *context) deleteTexture(t textureNative) {
 	c.ctx.DeleteTexture(uint32(t))
 }
 
-func (c *context) isTexture(t textureNative) bool {
-	return c.ctx.IsTexture(uint32(t))
-}
-
 func (c *context) newRenderbuffer(width, height int) (renderbufferNative, error) {
 	r := c.ctx.CreateRenderbuffer()
 	if r <= 0 {
@@ -344,10 +324,6 @@ func (c *context) newRenderbuffer(width, height int) (renderbufferNative, error)
 	return renderbuffer, nil
 }
 
-func (c *context) bindRenderbufferImpl(r renderbufferNative) {
-	c.ctx.BindRenderbuffer(gl.RENDERBUFFER, uint32(r))
-}
-
 func (c *context) deleteRenderbuffer(r renderbufferNative) {
 	if !c.ctx.IsRenderbuffer(uint32(r)) {
 		return
@@ -388,10 +364,6 @@ func (c *context) bindStencilBuffer(f framebufferNative, r renderbufferNative) e
 	return nil
 }
 
-func (c *context) setViewportImpl(width, height int) {
-	c.ctx.Viewport(0, 0, int32(width), int32(height))
-}
-
 func (c *context) deleteFramebuffer(f framebufferNative) {
 	if !c.ctx.IsFramebuffer(uint32(f)) {
 		return
@@ -407,14 +379,6 @@ func (c *context) deleteFramebuffer(f framebufferNative) {
 	c.ctx.DeleteFramebuffer(uint32(f))
 }
 
-func (c *context) newVertexShader(source string) (shader, error) {
-	return c.newShader(gl.VERTEX_SHADER, source)
-}
-
-func (c *context) newFragmentShader(source string) (shader, error) {
-	return c.newShader(gl.FRAGMENT_SHADER, source)
-}
-
 func (c *context) newShader(shaderType uint32, source string) (shader, error) {
 	s := c.ctx.CreateShader(shaderType)
 	if s == 0 {
@@ -431,10 +395,6 @@ func (c *context) newShader(shaderType uint32, source string) (shader, error) {
 	return shader(s), nil
 }
 
-func (c *context) deleteShader(s shader) {
-	c.ctx.DeleteShader(uint32(s))
-}
-
 func (c *context) newProgram(shaders []shader, attributes []string) (program, error) {
 	p := c.ctx.CreateProgram()
 	if p == 0 {
@@ -457,10 +417,6 @@ func (c *context) newProgram(shaders []shader, attributes []string) (program, er
 	return program(p), nil
 }
 
-func (c *context) useProgram(p program) {
-	c.ctx.UseProgram(uint32(p))
-}
-
 func (c *context) deleteProgram(p program) {
 	c.locationCache.deleteProgram(p)
 
@@ -470,10 +426,6 @@ func (c *context) deleteProgram(p program) {
 	c.ctx.DeleteProgram(uint32(p))
 }
 
-func (c *context) getUniformLocationImpl(p program, location string) uniformLocation {
-	return uniformLocation(c.ctx.GetUniformLocation(uint32(p), location))
-}
-
 func (c *context) uniformInt(p program, location string, v int) bool {
 	l := c.locationCache.GetUniformLocation(c, p, location)
 	if l == invalidUniform {
@@ -517,18 +469,6 @@ func (c *context) uniforms(p program, location string, v []uint32, typ shaderir.
 	return true
 }
 
-func (c *context) vertexAttribPointer(index int, size int, stride int, offset int) {
-	c.ctx.VertexAttribPointer(uint32(index), int32(size), gl.FLOAT, false, int32(stride), offset)
-}
-
-func (c *context) enableVertexAttribArray(index int) {
-	c.ctx.EnableVertexAttribArray(uint32(index))
-}
-
-func (c *context) disableVertexAttribArray(index int) {
-	c.ctx.DisableVertexAttribArray(uint32(index))
-}
-
 func (c *context) newArrayBuffer(size int) buffer {
 	b := c.ctx.CreateBuffer()
 	c.ctx.BindBuffer(gl.ARRAY_BUFFER, b)
@@ -543,14 +483,6 @@ func (c *context) newElementArrayBuffer(size int) buffer {
 	return buffer(b)
 }
 
-func (c *context) bindArrayBuffer(b buffer) {
-	c.ctx.BindBuffer(gl.ARRAY_BUFFER, uint32(b))
-}
-
-func (c *context) bindElementArrayBuffer(b buffer) {
-	c.ctx.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, uint32(b))
-}
-
 func (c *context) arrayBufferSubData(data []float32) {
 	s := unsafe.Slice((*byte)(unsafe.Pointer(&data[0])), len(data)*4)
 	c.ctx.BufferSubData(gl.ARRAY_BUFFER, 0, s)
@@ -560,51 +492,3 @@ func (c *context) elementArrayBufferSubData(data []uint16) {
 	s := unsafe.Slice((*byte)(unsafe.Pointer(&data[0])), len(data)*2)
 	c.ctx.BufferSubData(gl.ELEMENT_ARRAY_BUFFER, 0, s)
 }
-
-func (c *context) deleteBuffer(b buffer) {
-	c.ctx.DeleteBuffer(uint32(b))
-}
-
-func (c *context) drawElements(len int, offsetInBytes int) {
-	c.ctx.DrawElements(gl.TRIANGLES, int32(len), gl.UNSIGNED_SHORT, offsetInBytes)
-}
-
-func (c *context) maxTextureSizeImpl() int {
-	return c.ctx.GetInteger(gl.MAX_TEXTURE_SIZE)
-}
-
-func (c *context) flush() {
-	c.ctx.Flush()
-}
-
-func (c *context) texSubImage2D(t textureNative, args []*graphicsdriver.WritePixelsArgs) {
-	c.bindTexture(t)
-	for _, a := range args {
-		c.ctx.TexSubImage2D(gl.TEXTURE_2D, 0, int32(a.X), int32(a.Y), int32(a.Width), int32(a.Height), gl.RGBA, gl.UNSIGNED_BYTE, a.Pixels)
-	}
-}
-
-func (c *context) enableStencilTest() {
-	c.ctx.Enable(gl.STENCIL_TEST)
-}
-
-func (c *context) disableStencilTest() {
-	c.ctx.Disable(gl.STENCIL_TEST)
-}
-
-func (c *context) beginStencilWithEvenOddRule() {
-	c.ctx.Clear(gl.STENCIL_BUFFER_BIT)
-	c.ctx.StencilFunc(gl.ALWAYS, 0x00, 0xff)
-	c.ctx.StencilOp(gl.KEEP, gl.KEEP, gl.INVERT)
-	c.ctx.ColorMask(false, false, false, false)
-}
-
-func (c *context) endStencilWithEvenOddRule() {
-	c.ctx.StencilFunc(gl.NOTEQUAL, 0x00, 0xff)
-	c.ctx.StencilOp(gl.KEEP, gl.KEEP, gl.KEEP)
-	c.ctx.ColorMask(true, true, true, true)
-}
-
-func (c *context) isES() bool {
-	return c.ctx.IsES()
-}
diff --git a/internal/graphicsdriver/opengl/graphics.go b/internal/graphicsdriver/opengl/graphics.go
index 3496103cf..eaed4d6b8 100644
--- a/internal/graphicsdriver/opengl/graphics.go
+++ b/internal/graphicsdriver/opengl/graphics.go
@@ -20,6 +20,7 @@ import (
 
 	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
+	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/opengl/gl"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
 )
 
@@ -59,7 +60,7 @@ func (g *Graphics) Begin() error {
 func (g *Graphics) End(present bool) error {
 	// Call glFlush to prevent black flicking (especially on Android (#226) and iOS).
 	// TODO: examples/sprites worked without this. Is this really needed?
-	g.context.flush()
+	g.context.ctx.Flush()
 	return nil
 }
 
@@ -231,27 +232,34 @@ func (g *Graphics) DrawTriangles(dstID graphicsdriver.ImageID, srcIDs [graphics.
 		if err := destination.ensureStencilBuffer(); err != nil {
 			return err
 		}
-		g.context.enableStencilTest()
+		g.context.ctx.Enable(gl.STENCIL_TEST)
 	}
 
 	for _, dstRegion := range dstRegions {
-		g.context.scissor(
-			int(dstRegion.Region.X),
-			int(dstRegion.Region.Y),
-			int(dstRegion.Region.Width),
-			int(dstRegion.Region.Height),
+		g.context.ctx.Scissor(
+			int32(dstRegion.Region.X),
+			int32(dstRegion.Region.Y),
+			int32(dstRegion.Region.Width),
+			int32(dstRegion.Region.Height),
 		)
 		if evenOdd {
-			g.context.beginStencilWithEvenOddRule()
-			g.context.drawElements(dstRegion.IndexCount, indexOffset*2)
-			g.context.endStencilWithEvenOddRule()
+			g.context.ctx.Clear(gl.STENCIL_BUFFER_BIT)
+			g.context.ctx.StencilFunc(gl.ALWAYS, 0x00, 0xff)
+			g.context.ctx.StencilOp(gl.KEEP, gl.KEEP, gl.INVERT)
+			g.context.ctx.ColorMask(false, false, false, false)
+
+			g.context.ctx.DrawElements(gl.TRIANGLES, int32(dstRegion.IndexCount), gl.UNSIGNED_SHORT, indexOffset*2)
+
+			g.context.ctx.StencilFunc(gl.NOTEQUAL, 0x00, 0xff)
+			g.context.ctx.StencilOp(gl.KEEP, gl.KEEP, gl.KEEP)
+			g.context.ctx.ColorMask(true, true, true, true)
 		}
-		g.context.drawElements(dstRegion.IndexCount, indexOffset*2) // 2 is uint16 size in bytes
+		g.context.ctx.DrawElements(gl.TRIANGLES, int32(dstRegion.IndexCount), gl.UNSIGNED_SHORT, indexOffset*2) // 2 is uint16 size in bytes
 		indexOffset += dstRegion.IndexCount
 	}
 
 	if evenOdd {
-		g.context.disableStencilTest()
+		g.context.ctx.Disable(gl.STENCIL_TEST)
 	}
 
 	return nil
@@ -270,7 +278,7 @@ func (g *Graphics) NeedsRestoring() bool {
 	if runtime.GOOS == "js" {
 		return false
 	}
-	return g.context.isES()
+	return g.context.ctx.IsES()
 }
 
 func (g *Graphics) NeedsClearingScreen() bool {
diff --git a/internal/graphicsdriver/opengl/graphics_glfw.go b/internal/graphicsdriver/opengl/graphics_glfw.go
index 0b34343a9..52b9d71ce 100644
--- a/internal/graphicsdriver/opengl/graphics_glfw.go
+++ b/internal/graphicsdriver/opengl/graphics_glfw.go
@@ -21,7 +21,7 @@ import (
 )
 
 func (g *Graphics) SetGLFWClientAPI() {
-	if g.context.isES() {
+	if g.context.ctx.IsES() {
 		glfw.WindowHint(glfw.ClientAPI, glfw.OpenGLESAPI)
 		glfw.WindowHint(glfw.ContextVersionMajor, 2)
 		glfw.WindowHint(glfw.ContextVersionMinor, 0)
diff --git a/internal/graphicsdriver/opengl/image.go b/internal/graphicsdriver/opengl/image.go
index 762bf2c9f..6c846491e 100644
--- a/internal/graphicsdriver/opengl/image.go
+++ b/internal/graphicsdriver/opengl/image.go
@@ -19,6 +19,7 @@ import (
 
 	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
+	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/opengl/gl"
 )
 
 type Image struct {
@@ -37,7 +38,7 @@ func (i *Image) ID() graphicsdriver.ImageID {
 }
 
 func (i *Image) IsInvalidated() bool {
-	return !i.graphics.context.isTexture(i.texture)
+	return !i.graphics.context.ctx.IsTexture(uint32(i.texture))
 }
 
 func (i *Image) Dispose() {
@@ -132,9 +133,14 @@ func (i *Image) WritePixels(args []*graphicsdriver.WritePixelsArgs) error {
 	// glFlush is necessary on Android.
 	// glTexSubImage2D didn't work without this hack at least on Nexus 5x and NuAns NEO [Reloaded] (#211).
 	if i.graphics.drawCalled {
-		i.graphics.context.flush()
+		i.graphics.context.ctx.Flush()
 	}
 	i.graphics.drawCalled = false
-	i.graphics.context.texSubImage2D(i.texture, args)
+
+	i.graphics.context.bindTexture(i.texture)
+	for _, a := range args {
+		i.graphics.context.ctx.TexSubImage2D(gl.TEXTURE_2D, 0, int32(a.X), int32(a.Y), int32(a.Width), int32(a.Height), gl.RGBA, gl.UNSIGNED_BYTE, a.Pixels)
+	}
+
 	return nil
 }
diff --git a/internal/graphicsdriver/opengl/locationcache.go b/internal/graphicsdriver/opengl/locationcache.go
index b14943d7a..6a82581b9 100644
--- a/internal/graphicsdriver/opengl/locationcache.go
+++ b/internal/graphicsdriver/opengl/locationcache.go
@@ -30,7 +30,7 @@ func (c *locationCache) GetUniformLocation(context *context, p program, location
 	}
 	l, ok := c.uniformLocationCache[p][location]
 	if !ok {
-		l = context.getUniformLocationImpl(p, location)
+		l = uniformLocation(context.ctx.GetUniformLocation(uint32(p), location))
 		c.uniformLocationCache[p][location] = l
 	}
 	return l
diff --git a/internal/graphicsdriver/opengl/program.go b/internal/graphicsdriver/opengl/program.go
index 404f4b4f2..20cef3de1 100644
--- a/internal/graphicsdriver/opengl/program.go
+++ b/internal/graphicsdriver/opengl/program.go
@@ -20,6 +20,7 @@ import (
 	"unsafe"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
+	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/opengl/gl"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
 )
 
@@ -70,12 +71,12 @@ func (a *arrayBufferLayout) newArrayBuffer(context *context) buffer {
 // enable starts using the array buffer.
 func (a *arrayBufferLayout) enable(context *context) {
 	for i := range a.parts {
-		context.enableVertexAttribArray(i)
+		context.ctx.EnableVertexAttribArray(uint32(i))
 	}
 	total := a.totalBytes()
 	offset := 0
 	for i, p := range a.parts {
-		context.vertexAttribPointer(i, p.num, total, offset)
+		context.ctx.VertexAttribPointer(uint32(i), int32(p.num), gl.FLOAT, false, int32(total), offset)
 		offset += floatSizeInBytes * p.num
 	}
 }
@@ -84,7 +85,7 @@ func (a *arrayBufferLayout) enable(context *context) {
 func (a *arrayBufferLayout) disable(context *context) {
 	// TODO: Disabling should be done in reversed order?
 	for i := range a.parts {
-		context.disableVertexAttribArray(i)
+		context.ctx.DisableVertexAttribArray(uint32(i))
 	}
 }
 
@@ -134,7 +135,7 @@ func (s *openGLState) reset(context *context) error {
 	}
 
 	s.lastProgram = 0
-	context.useProgram(0)
+	context.ctx.UseProgram(0)
 	for key := range s.lastUniforms {
 		delete(s.lastUniforms, key)
 	}
@@ -143,10 +144,10 @@ func (s *openGLState) reset(context *context) error {
 	// and must not be deleted by DeleteBuffer.
 	if runtime.GOOS != "js" {
 		if s.arrayBuffer != 0 {
-			context.deleteBuffer(s.arrayBuffer)
+			context.ctx.DeleteBuffer(uint32(s.arrayBuffer))
 		}
 		if s.elementArrayBuffer != 0 {
-			context.deleteBuffer(s.elementArrayBuffer)
+			context.ctx.DeleteBuffer(uint32(s.elementArrayBuffer))
 		}
 	}
 
@@ -199,11 +200,11 @@ func (g *Graphics) textureVariableName(idx int) string {
 // useProgram uses the program (programTexture).
 func (g *Graphics) useProgram(program program, uniforms []uniformVariable, textures [graphics.ShaderImageCount]textureVariable) error {
 	if g.state.lastProgram != program {
-		g.context.useProgram(program)
+		g.context.ctx.UseProgram(uint32(program))
 		if g.state.lastProgram == 0 {
 			theArrayBufferLayout.enable(&g.context)
-			g.context.bindArrayBuffer(g.state.arrayBuffer)
-			g.context.bindElementArrayBuffer(g.state.elementArrayBuffer)
+			g.context.ctx.BindBuffer(gl.ARRAY_BUFFER, uint32(g.state.arrayBuffer))
+			g.context.ctx.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, uint32(g.state.elementArrayBuffer))
 		}
 
 		g.state.lastProgram = program
@@ -211,7 +212,7 @@ func (g *Graphics) useProgram(program program, uniforms []uniformVariable, textu
 			delete(g.state.lastUniforms, k)
 		}
 		g.state.lastActiveTexture = 0
-		g.context.activeTexture(0)
+		g.context.ctx.ActiveTexture(gl.TEXTURE0)
 	}
 
 	for _, u := range uniforms {
@@ -258,7 +259,7 @@ loop:
 		})
 		g.context.uniformInt(program, g.textureVariableName(i), idx)
 		if g.state.lastActiveTexture != idx {
-			g.context.activeTexture(idx)
+			g.context.ctx.ActiveTexture(uint32(gl.TEXTURE0 + idx))
 			g.state.lastActiveTexture = idx
 		}
 
diff --git a/internal/graphicsdriver/opengl/shader.go b/internal/graphicsdriver/opengl/shader.go
index 965f02ce2..06336e269 100644
--- a/internal/graphicsdriver/opengl/shader.go
+++ b/internal/graphicsdriver/opengl/shader.go
@@ -18,6 +18,7 @@ import (
 	"fmt"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
+	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/opengl/gl"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/glsl"
 )
@@ -54,17 +55,17 @@ func (s *Shader) Dispose() {
 func (s *Shader) compile() error {
 	vssrc, fssrc := glsl.Compile(s.ir, s.graphics.context.glslVersion())
 
-	vs, err := s.graphics.context.newVertexShader(vssrc)
+	vs, err := s.graphics.context.newShader(gl.VERTEX_SHADER, vssrc)
 	if err != nil {
 		return fmt.Errorf("opengl: vertex shader compile error: %v, source:\n%s", err, vssrc)
 	}
-	defer s.graphics.context.deleteShader(vs)
+	defer s.graphics.context.ctx.DeleteShader(uint32(vs))
 
-	fs, err := s.graphics.context.newFragmentShader(fssrc)
+	fs, err := s.graphics.context.newShader(gl.FRAGMENT_SHADER, fssrc)
 	if err != nil {
 		return fmt.Errorf("opengl: fragment shader compile error: %v, source:\n%s", err, fssrc)
 	}
-	defer s.graphics.context.deleteShader(fs)
+	defer s.graphics.context.ctx.DeleteShader(uint32(fs))
 
 	p, err := s.graphics.context.newProgram([]shader{vs, fs}, theArrayBufferLayout.names())
 	if err != nil {
diff --git a/internal/graphicsdriver/opengl/shader_notjs.go b/internal/graphicsdriver/opengl/shader_notjs.go
index 307a17621..e44d736f8 100644
--- a/internal/graphicsdriver/opengl/shader_notjs.go
+++ b/internal/graphicsdriver/opengl/shader_notjs.go
@@ -21,7 +21,7 @@ import (
 )
 
 func (c *context) glslVersion() glsl.GLSLVersion {
-	if c.isES() {
+	if c.ctx.IsES() {
 		return glsl.GLSLVersionES100
 	}
 	return glsl.GLSLVersionDefault